1. Field of the Invention
The present invention relates generally to a system and method for positioning control for vehicles, such as helicopters, using Global Navigation Satellite System (GNSS) vector guidance.
2. Description of the Related Art
Helicopters with winches are used in rescue operations, e.g., at sea for winching personnel off of heaving ships, rescues from cliff faces and in ravines for climbers and hikers. They are also used in lifting and positioning heavy objects in locations with limited accessibility. Examples include placing antennas on communications towers and placing heating, ventilating and air-conditioning (HVAC) equipment on rooftops, including high-rise buildings.
These operations are often carried out in less than ideal conditions, e.g.: at night; with low visibility; and in windy and rainy environments. These conditions make the positioning of the winch difficult to maintain during critical periods of the rescue or lift.
GNSS can effectively guide vehicles, such as helicopters, to work sites, but once speed is reduced the heading generated by GNSS is unreliable. Positioning discrepancies in connection with air-to-ground operations can also occur because winches are normally offset by several meters in X, Y and Z directions, which varies the desired winch position relative to the helicopter heading.